The most important objectives of wireless communications, broadcasting, telemetry, infrared and in general “radio” systems as well as “wired” systems include: power and bandwidth or spectrum efficiency combined with robust Bit Error Rate (BER) performance in a noisy and/or strong interference environment. These system objectives are specified in numerous systems including wireless communications and cellular systems, satellite systems, mobile and telemetry systems, broadcasting systems, cable, fiber optics and practically all communication transmission systems. A partial list of publications, references, and patents are provided separately below. The cited publications, references [1-23] and patents [P1-P8], and the references within the aforementioned publications contain definitions and descriptions of many terms used in this new patent disclosure and for this reason these conventional terms and definitions will be described only briefly, and highlighted on a case by case basis.
Robust or high performance Bit Error Rate (BER) specifications and/or objectives are frequently expressed in terms of the required BER as a function of Energy per Bit (Eb) divided by Noise Density or simply noise (No), that is, by the BER=f (Eb/No) expression. Low cost, reduced size, and compatibility and/or interoperability with other conventional or previously standardized systems, also known as “legacy systems,” are highly desired. Several standardization organizations have adopted modulation techniques such as conventional Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Offset Quadrature Phase Shift Keying (OQPSK) also designated as Staggered Quadrature Phase Shift Keying (SQPSK), and pi/4-QPSK (or π/4-QPSK) techniques including differential encoding variations of the same. See publications [1-23] and referenced patents [P1-P8] for examples and further description. For spectrally or spectrum efficient signaling (such as band-limited signaling), these conventional methods exhibit a large envelope fluctuation of the modulated signal, and thus have a large increase in peak radiated power relative to the average radiated power. For these reasons such systems are not suitable for BRA, robust BER performance NLA operated RF power efficient systems.
Within the present state of the technology, for numerous BRA Transceiver applications, it is not practical to introduce band-pass filtering after the NLA power efficient Radio Frequency (RF) final amplifier stage. Here we are using the term “Radio Frequency” (RF) in its broadest sense, implying that we are dealing with a modulated signal. The RF could be, for example, as high as the frequency of infrared or fiber optic transmitters; it could be in the GHz range, for example, between 1 GHz and 300 GHz or more, or it could be in the MHz range, for example, between about 1 MHz and 999 MHz, or just in the kHz range. The term RF could even apply to Quadrature Modulated (abbreviated “QM” or “QMOD”) Base-Band (BB) signals or to Intermediate Frequency (IF) signals.
In conventional BPSK, QPSK, OQPSK or SQPSK, and differentially-encoded phase-shift keying systems variants of these systems, such as DBPSK and DQPSK, as well as in pi/4-DQPSK and trellis coded QPSK and DQPSK, large envelope fluctuations require linearized (LIN) or highly linear transmitters including frequency up-converters and RF power amplifiers and may require expensive linear receivers having linear Automatic Gain Control (AGC) circuits. A transmitter NLA reduces the time domain envelope fluctuation of conventional QPSK type of band-limited signals and this reduction of the envelope fluctuation, being a signal distortion, is the cause of spectral restoration or spectral regrowth and the cause of unacceptably high levels of out-of-band spectral energy transmission, also known as out-of-band interference. Additionally, for conventional BPSK, QPSK, and also Quadrature Amplitude Modulation number (QAM) signals, undesired in-phase channel (I) to quadrature channel (Q) crosstalk is generated. This crosstalk degrades the BER=f(Eb/N0) performance of the modulated radio transmitter.
Experimental work, computer simulation, and theory documented in many recent publications indicates that for band-limited and standardized BPSK, QPSK, OQPSK or SQPSK or pi/4-QPSK, and QAM system specifications, very linear amplifiers are required to avoid the pitfalls of spectral restoration and of BER degradation. Linearized or linear amplifiers are less RF power efficient (during the power “on” state, power efficiency being defined as the transmit RF power divided by DC power), are considerably more expensive and/or having less transmit RF power capability, are larger in size, and are not as readily available as NLA amplifiers. The advantages of NLA over LIN amplifiers are even more dramatic at higher RF frequencies, such as frequencies above about 1 GHz for applications requiring low dc voltage, for example applications or systems operating on size “AA” batteries having only 1.5 Volt dc and for high RF modulated power requirements, for example transmit RF power in the 0.5 Watt to 100 Watt range.
Published references [P1 to P8] and [1 to 23] include additional background information. These references include descriptions of binary-state and multiple-state Transmitter/Receiver (Transceiver) or for short (“TR”) systems that are suitable for NLA. In the aforementioned references Processors, Modems, Transmitters, Receivers and Transceivers, suitable for NLA, have been described, defined and designated as first generation of Feher patented Quadrature Shift Keying (FQPSK). For example, in reference [22] published on May 15, 1999 the authors Drs. M. K. Simon and T. Y. Yan of JPL/NASA-Caltech present a detailed study of Unfiltered Feher-Patented Quadrature Phase Shift Keying (FQPSK). In references [1-22] and patents #[P1-P8] numerous first generation FQPSK technology based terms, and terms other than the FQPSK abbreviation/acronym have been used. In addition to FQPSK Transceivers, these first generation of systems have been also described and/or defined as: Feher's Minimum Shift Keying (FMSK), Feher's Frequency Shift Keying (FFSK), Feher's Gaussian Minimum Shift Keying (FGMSK), Feher's Quadrature Amplitude Modulation (FQAM) and/or Feher's (F) Modulation Amplification (FMOD). Additionally terms such as Superposed Quadrature Amplitude Modulation (SQAM), Intersymbol Interference and Jitter Free (IJF) and/or IJF-OQPSK have been also described in Feher et al's prior patents and publications, each of which is incorporated by reference.
In the cited patents and other references, among the aforementioned abbreviations, acronyms, designation, terms and descriptions the “FQPSK” abbreviation/term has been most frequently used to describe in most generic terms one or more of these afore described Feher or Feher et al. first generation of Non-Linearly Amplified (NLA) inventions and technologies. The 1st generation of FQPSK systems have significantly increased spectral efficiency and enhanced end-to-end performance as compared to other NLA systems. RF power advantages, robust BER performance, and NLA narrow spectrum without the pitfalls of conventional BPSK and DBPSK, QPSK and OQPSK have been attained with these 1st generation FQPSK systems and methods. The generic 1st generation terms such as FQPSK, as well as other previously mentioned terms/acronyms are retained and used in this description to describe the new BRA, Code Selectable (CS), Modem Format Selectable (MFS) and modulation-demodulation Mis-Matched (MM) filtered architectures and embodiments of “2nd generation” FQPSK Transceivers.
While these earlier issued patents and publications describe material of a background nature, they do not disclose the original new enhanced performance bit rate agile and modulation agile/selectable technologies disclosed in this new invention.
Partial List of Relevant Literature
Several references, including United States patents, International or Foreign Patents, publications, conferences proceedings, and other references are identified herein to assist the reader in understanding the context in which the invention is made, some of the distinctions of the inventive structures and methods over that which was known prior to the invention, and advantages over the invention. No representation is made as to whether the contents of the cited references represent prior-art as several of the cited references have a date after the effective filing date (priority date) of this patent application. This list is intended to be illustrative rather than exhaustive.
United States Patents
[P1] U.S. Pat. No. 5,784,402 Issued July 1998 to Feher
[P2] U.S. Pat. No. 5,491,457 Issued February 1996 to Feher
[P3] U.S. Pat. No. 4,720,839 Issued January 1988 to Feher et al.
[P4] U.S. Pat. No. 4,644,565 Issued February 1987 to Seo/Feher [P5] U.S. Pat. No. 4,567,602 Issued January 1986 to Kato/Feher
[P6] U.S. Pat. No. 4,350,379 Issued September 1982 to Feher [P7] U.S. Pat. No. 4,339,724 Issued July 1982 to Feher
[P8] U.S. Pat. No. 3,954,926 Issued March 1976 to Feher
Foreign Patent Documents:
[PF1] Canadian Patent No. 1130871 August 1982 [PF2] Canadian Patent No. 1211517 September 1986
[PF3] Canadian Patent No. 1265851 February 1990
Other Publications:
    1. Feher, K.: Wireless Digital Communications: Modulation Spread Spectrum. Prentice Hall, 1995.    2. Feher, K.: Digital Communications: Satellite/Earth Station Engineering. Prentice Hall, 1983. Available from Crestone Engineering—Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.    3. Feher, K.: Advanced Digital Communications: Systems and Signal Processing. Prentice Hall, 1987. Available from Crestone Engineering—Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.    4. Feher, K.: Digital Communications: Microwave Applications. Prentice Hall 1981. Since 1997 available from Crestone Engineering—Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.    5. Feher, K. and Engineers of Hewlett-Packard: Telecommunications Measurements, Analysis, and Instrumentation: Prentice Hall 1987. Since 1997 reprints have been available from Crestone Engineering—Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.    6. Feher, K., Emmenegger, H.: “FQPSK Use for Electronic News Gathering (ENG), Telemetry and Broadcasting,” Proc. of the National Association of Broadcasters NAB'99 Broadcast Engineering Conference, Las Vegas, Apr. 19-22, 1999.    7. Feher, K.: “FQPSK Doubles Spectral Efficiency of Operational Systems: Advances, Applications, Laboratory and Initial Air-to-Ground Flight Tests” (Date of Submission: Aug. 14, 1998). Proc. of the International Telemetry Conference, ITC-98 ITC USA 98, San Diego, Calif., Oct. 26-29, 1998.    8. W. Gao, S. H. Wang, K. Feher: “Blind Equalization for FQPSK and FQAM Systems in Multipath Frequency Selective Fading Channels,” Proc. Internat. Telemetry Conf. ITC/USA'99, Oct. 25-28, 1999, Las Vegas, Nev.    9. Terziev, G., Feher, K.: “Adaptive Fast Blind Feher Equalizers (FE) for FQPSK,” Proc. Of the International Telemetry Conference ITC/USA'99, Oct. 25-28, 1999, Las Vegas, Nev.    10. Feher, K.: “FQPSK Transceivers Double the Spectral Efficiency of Wireless and Telemetry Systems” Applied Microwave & Wireless Journal, June 1998.    11. Seo, J-S. and K. Feher: “Bandwidth Compressive 16-State SQAM Modems through Saturated Amplifiers,” IEEE Radio Commun., ICC '86, Toronto, June 1986.    12. Kato, S. and K. Feher: “XPSK: A new cross-correlated PSK,” IEEE Trans. Com., May 1983.    13. Law, E. L., U.S. Navy: “Robust Bandwidth Efficient Modulation” European Telemetry Conference, ETC-98, Germany, May 1998.    14. Feher, K.: “FQPSK Doubles the Spectral Efficiency. of Operational Telemetry Systems,” European Telemetry Conference, ETC-98, May 1998, Germany.    15. Do, G. and K. Feher: “FQPSK-GMSK: Wireless System Tests an ACI Environment,” Proc. of Wireless Symposium, Santa Clara, Calif., Feb. 9-13, 1998.    16. Law, E. and K. Feher: “FQPSK versus PCM/FM for Aeronautical Telemetry Applications: Spectral Occupancy and Bit Error Probability Comparisons” Proc. of ITC-97, Las Vegas, October 1997.    17. Feher, K “FQPSK Doubles Spectral Efficiency of Telemetry: Advances and Initial Air to Ground Flight Tests,” ITC USA 98, Proc. of the Internat. Telemetry Conference, San Diego, October 1998.    18. Law, E. and K. Feher: “FQPSK versus PCM/FM for Aeronautical Telemetry Applications; Spectral Occupancy and Bit Error Probability Comparisons,” Proc. of the Internat. Telemetry Conf., Las Vegas, Nev., Oct. 27-30, 1997.    19. Martin, W. L., T-Y. Yan, L. V. Lam: “Efficient Modulation Study at NASA/JPL,” Proc. of the Tracking, Telemetry & Command Systems Conference, European Space Agency (ESA), June 1998.    20. Law, E. L., ITC-98 Session Chair: “RCC Alternate Standards and IRIG106 update,” Briefings by DoD during ITC/USA 98 Internat. Telemetry Conference, San Diego, October 1998.    21. K. Feher: “FQPSK Doubles Spectral Efficiency of Operational Systems: Advances, Applications, Laboratory and Initial Air to Ground Flight Tests”, File: ITC.98.Final Paper. Rev. 5. Aug. 14, 1998 (Date of Submission) for publication in the Proc. of the International Telemetering Conference, ITC-98; San Diego, Oct. 26-29, 1998    22. Simon, M. K, Yan, T. Y. “Performance Evaluation and Interpretation of Unfiltered Feher-Patented Quadrature Phase-Shift Keying (FQPSK),” California Institute of Technology, JPL-NASA publication, TMD Progress Report 42-137, Pasadena, Calif., May 15, 1999.    23. Winters, J. H.: “Adaptive Antenna Arrays for Wireless Systems,” Tutorial Notes presented/distributed at the 1999 IEEE Vehicular Technology Conference, Houston, Tex., May 16, 1999.